Evaluation carried out on four types of vehicles: the 44-tonne heavy goods vehicle, the 18-metre articulated bus, the regional bus and the 75-tonne tracked excavator.
This article is the result of a study on the development of the hydrogen sector. It aims to evaluate and compare the energy, economic and environmental relevance of the two possible ways of using hydrogen in motor vehicles: its use in a fuel cell (FC), on the one hand, or its combustion in a combustion engine, on the other.
Preambule
In order to reduce greenhouse gas emissions and pollutant gases from the transport sector that are harmful to living organisms and the environment, alternative energy sources to petroleum-based fuels have been developed in recent years. Electric vehicles are gradually being introduced into the regulations of many countries.
In terms of decarbonising transport, battery-powered vehicles are very energy efficient and should therefore be favoured when their use meets the user's needs.
However, for intensive use or high energy consuming vehicles, the battery vehicle may not be suitable for reasons of insufficient range or charging time incompatible with the needs of the service. Being very energy intensive, the size and mass of the batteries have to be adapted accordingly and can therefore exceed several tons. This becomes problematic when the purpose of the vehicle is to transport goods or passengers, for example.
Hydrogen heat engine. Hydrogen is a very good fuel. It is therefore possible to burn it in a combustion engine, in a process similar to the combustion of fossil fuels. combustion engine, in a process similar to the combustion of fossil fuels. In this case, the chemical energy. In this case, the chemical energy is converted directly into mechanical energy via the combustion engine. The study was conducted with a internal combustion engine, or even hybrid thermal-electric operation
Hydrogen fuel cell (FC). Another way is to transform chemical energy into electrical energy, and to use this electrical energy in an electrical machine to transform it into mechanical energy. An electrical machine to transform it into mechanical energy. This is the principle of fuel cell vehicles (FC). The study was carried out with a hydrogen fuel cell of the proton exchange membrane type.
Evaluation carried out on four types of vehicles: the 44-tonne heavy goods vehicle, the 18-metre articulated bus, the regional bus and the 75-tonne tracked excavator.
These vehicles consume large amounts of energy and often require fast refuelling times, needs that are difficult to meet with a battery electric vehicle. Difficult to meet with a battery electric vehicle. The use of hydrogen as a substitute for fossil fuels or the battery may be a solution.
Energetic evaluation
The fuel consumption of the four types of vehicles is evaluated over different duty cycles. Parametric variations (power of the fuel cell or of the combustion engine in the case of a hybrid engine, energy capacity of the battery) make it possible to assess the impact of the powertrain design on consumption.
These heavy machines, at their peak, consume large amounts of energy and require fast and convenient refuelling times, needs that are difficult to meet with a battery electric vehicle. The use of hydrogen as a substitute for fossil fuels or the battery may be a solution.
However, vehicles equipped with a fuel cell are 10 to 40% more energy efficient, depending on use, than those powered by a hydrogen combustion engine.
Economic evaluation
The economic evaluation is based on the TCO (Total Cost of Ownership) indicator and aggregates the different cost items. Sensitivity analyses on the key parameters of the evaluation - such as the price of hydrogen and vehicle life.
It can be seen that the switch to hydrogen leads to a 1.5 to 3-fold increase in TCO for the four vehicles evaluated compared to the reference diesel configuration. There is a slight TCO advantage for the hydrogen engine over the fuel cell (FC), as the high investment cost of the fuel cell is not offset by the lower fuel consumption.
The main ways to reduce the TCO gap with the diesel configuration are lowering the price of hydrogen and the fuel cell, while improving the efficiency of the combustion engine and the FC seem to have a limited effect on the TCO.
The investment effort required to switch to a fuel cell vehicle remains high at present, however, as demand continues to grow and policy measures to limit the use of diesel engines - banned in 2035 - mean that investment in fuel cells is becoming increasingly profitable without manufacturers having to charge high prices to customers.
Environmental assessment
The environmental assessment is based on the life cycle assessment (LCA) methodology and compares the greenhouse gas (GHG) emissions of hydrogen solutions for two types of vehicles: heavy duty and articulated buses.
Note:
Considering hydrogen obtained by electrolysis with locally produced electricity, hydrogen vehicles have a significantly lower impact than diesel vehicles. In addition, the impacts related to hydrogen production account for most of the GHG emissions over their life cycle. This favours fuel cell vehicles, which have lower hydrogen consumption than combustion vehicles. The use of renewable hydrogen can further halve the lifecycle GHG emissions of fuel cell and hydrogen-powered thermal vehicles, compared to the use of low-carbon, electrolytically produced hydrogen.
Our conclusion
In the next twenty years, fossil fuel engines (Diesel, etc...) may no longer be allowed in Europe for self-propelled machines. Manufacturers are moving towards engines using non-polluting or low-polluting energy sources. For vehicles used by the general public, the hydrogen fuel cell could validly replace the current combustion engines and even the current electric cars.
For heavy machinery such as excavators, construction machinery and heavy trucks, the hydrogen fuel cell engine seems to be the obvious choice, or a hybrid system: a hydrogen fuel cell engine coupled with fuel cells that will be installed in a modular fashion in the machinery.